GB2377688A

GB2377688A - Lifting platform

Info

Publication number: GB2377688A
Application number: GB0112260A
Authority: GB
Inventors: Robert Bolderson
Original assignee: WHEELBASE ENGINEERING Ltd
Current assignee: WHEELBASE ENGINEERING Ltd
Priority date: 2001-05-19
Filing date: 2001-05-19
Publication date: 2003-01-22
Anticipated expiration: 2021-05-19
Also published as: GB0112260D0; GB2377688B

Abstract

A lifting mechanism for use within a load-carrying road vehicle has a platform (8) which links opposite free-standing upright side frames (2, 3). The frames (2, 3) have upright guide members (4) which are slidably engaged by guide elements (11) attached to the platform (8). The platform (8) can move up and down powered by a motor (12) carried by the lifting mechanism. The mechanism can also move forwards and backwards along the vehicle load-supporting floor, for example on rollers (7). Preferably, the platform is raised by chains 14,18 and sprockets 13,19.

Description

LIFTING MECHANISM This invention relates to a lifting mechanism for powered lifting of loads, particularly although not exclusively, for use in load-carrying road vehicles.

There is a requirement for power assistance in the loading and unloading of stacked articles in load-carrying areas of lorries and road trailers.

It is known to use wholly separate lifting mechanisms of the nature of fork lift trucks. Such mechanisms however can require much space in the load-carrying area for manoeuvring and may not therefore be convenient to use.

It is also known to use lifting platforms structurally incorporated within the vehicle, e. g. as described in GB-2279917-B. However, these platforms can necessitate substantial modification of the vehicle structure and may not therefore be convenient to install.

An object of the present invention is to provide an effective lifting mechanism which is convenient to use and install.

According to the invention therefore there is provided a lifting mechanism comprising opposed free-standing upright side frames, each such frame having at least one elongate guide member, a platform structure extending transversely between the side frames, elongate guide elements being provided on the platform structure for guidable connection with the

said guide members to interconnect the platform structure and side frames whilst permitting upwards and downwards movement of the platform structure relative to the side frames, the frames being adapted for movement at least forwards and backwards along a supporting floor surface, and power means for powering said movement of the platform structure in at least said upwards direction, said power means being mounted relative to the frames so as to be movable forwards and backwards therewith.

With this arrangement, in so far as the opposed free-standing side frames provide support and forwards/backwards movement, powered lifting can be achieved with a mechanism which can be conveniently manoeuvred and which is convenient to install. There is no essential requirement for an obtrusive drive arrangement to move the mechanism forwards and backwards, nor is there necessarily any requirement for incorporation of the mechanism into any separate structure such as the body of chassis of a load-carrying road vehicle.

Preferably each frame has two upright guide members and the platform structure has two guide elements for each frame.

The guide members of each frame may be of a common height and may be linked by top and bottom cross-members. The guide members may be parallel to each other, and preferably are vertical. The cross-members may also be parallel to each other and are preferably horizontal. The guide

elements may be of a common length.

In a particularly preferred embodiment each guide member is a tube, such as a polished stainless steel tube, and each guide element is a sleeve which fits slidably around the respective tube.

With regard to the platform structure, this may take any suitable form. Thus it may comprise an openwork frame structure or a covered frame.

Preferably the platform structure comprises a rectangular frame having interconnected elongate peripheral members, with an overlying support floor comprising boards or the like.

The platform structure may form the sole interconnection between the side frames, stability being achieved by virtue of the longitudinal interconnection between the guide elements and guide members.

Alternatively additional interconnections may be provided.

With regard to the movement of the side frames on the floor surface, this may be achieved with the assistance of rollers or wheels on the side frames engageable with the floor surface. Guide tracks or other arrangements may be provided for guiding movement of the lifting mechanism along a desired path.

Locking means may be provided for retaining the lifting mechanism in position on the floor surface. This locking means may comprise means for preventing rotation of the aforesaid wheels or rollers (e. g. in the form of

a brake) or a device for frictional or interlocking engagement with the floor surface or other adjacent structure.

With regard to the power means this is arranged for powering movement of the platform at least in the upwards direction. Movement downwards may also be powered or may occur under gravity with, if necessary, a frictional device or brake being provided to limit rate of descent.

The power means may have a motor which may be an electric motor powered by an on-board battery or by connection to a nearby power source. Alternatively, a hydraulic or pneumatic motor driven by an on-board or nearby source of compressed fluid may be used.

The motor may be geared and may be connected to a chain or belt drive connected between the platform structure and at least one (and preferably both) side frames.

In a particularly preferred embodiment the motor is mounted on the platform structure and is connected via one or more shafts to one or more toothed sprockets drivably engageable with at least one chain extending upwardly and fixed at its ends respectively to top and bottom positions on a respective said frame. There may be two shafts engageable at opposite ends with two chains on each frame.

It is visualised that the lifting mechanism will find particular use in load-carrying road vehicles such as lorries and trailers, in which case the

frames may be arranged at opposite sides of the load supporting floor of the vehicle.

The invention will now be described further by way of example only and with reference to the single figure of the accompanying drawings which is a diagrammatic perspective view of one form of a lifting mechanism according to the invention.

The lifting mechanism shown in the drawing is for use on the loadsupporting floor of a road trailer or lorry.

The longitudinal edge regions 1 of the floor are shown in broken lines in the drawing. Side walls may extend upwardly at such edge regions.

The lifting mechanism comprises two opposed upright side frames 2,3.

Each side frame 2,3 has two vertical guide members 4 defined by circular cross-section polished stainless steel tubes, and top and bottom horizontal square-section member 5,6 fixed at their ends to the respective ends of the tubes 4.

The bottom members 6 are provided with rollers 7 rotatably mounted beneath the members 6.

A platform structure 8 extends between the frames 2,3 so as to hold the frames vertically upright and in alignment with each other.

The platform structure 8 comprises a horizontal rectangular frame defined by two long square section members 9 linked by two shorter square

section side members 10 extending at right angles to the long members 9.

The side members 10 are fixed at their ends to inner sides of the long members 9 spaced slightly from the ends of the long members 9.

Metal circular-section tubular sleeves 11 are fixed to the ends of the long members 9 so as to extend vertically upwardly therefrom.

These sleeves 11 fit around the tubes 4 in close sliding fit therewith.

The sleeves 11 are of such a length as to hold the side frames 2,3 vertically.

The platform frame supports boarding or the like to provide an upper load-supporting surface (not shown). Beneath this, within the frame there is mounted centrally (on a support structure not shown) a geared electric motor 12 connected by sprockets 13 to two drive chains 14 which in turn are connected to sprockets 15 on two drive shafts 16.

The drive shafts 16 extend longitudinally alongside the long members 9 at the inner sides thereof and pass through bearings in the end regions of the shorter members 10, terminating with toothed sprockets 17 at outer sides of the shorter members 10.

Each side frame 2,3 has two chains 18 which run vertically between fixed points on the upper and lower members 5,6 adjacent to the inner sides of the tubes 4. The chains 18 extend along a stepped path by passing beneath the sprockets 17 at the ends of the shafts 16 and then over further sprockets 19 rotatably mounted on the shorter members 10 adjacent to and

inwardly of the shaft sprockets 17.

The electric motor 12 is connected to a source of electric power which may be an adjacent battery mounted on the platform 8 or which may be a nearby source (e. g. the vehicle power source) via a cable. Switches are provided at appropriate positions whereby a person standing on or near to the platform 8 can switch the motor on and off. Limit switches may also be provided whereby power is switched off at one or more limit positions of the platform 8.

The platform 8 is shown in a lower position in which articles can be easily loaded onto or removed from the platform.

By operating the motor 12, the platform 8 can be driven upwardly by rotation of the shafts 16 to cause the sprockets 17 to rotatably engage the chains 18.

When the platform 8 has attained a desired height the motor 12 can be switched off whereby the platform 8 retains its position by the friction inherent in the drive arrangement and/or by automatic operation of a brake.

In the elevated position articles can be readily loaded on to or removed from the tops of stacks of such articles.

The platform 8 can then be returned to its lower position by operating the motor 12 in reverse to drive the platform 8 downwardly, if necessary after first (or simultaneously) releasing the brake (manually or automatically).

The aforementioned rollers 7 permit movement of the lifting mechanism along the length of floor surface. A brake arrangement or the like may be provided to hold the mechanism in position for example by braking or retracting the rollers 7 or by establishing a frictional engagement or interlock between the frames and the floor or other part of the vehicle.

If desired the rollers 7 may run within or on tracks in the floor for guidance, although this is not essential.

If desired also the side frames 2,3 may be located close to the side edges 1 of the floor surface whereby guidance and/or support may be achieved on the usual side supports (raves) of the vehicle chassis and/or by temporary or permanent interengagement with side walls of the vehicle body, although this is not essential.

With the arrangement described above the lifting mechanism can be installed and operated conveniently within the loading area of a loadcarrying vehicle.

It is of course to be understood that the invention is not intended to be restricted to the details of the above embodiment which are described by way of example only.

Claims

CLAIMS 1. A lifting mechanism comprising opposed free standing upright side frames, each such frame having at least one elongate guide member, a platform structure extending transversely between the side frames, elongate guide elements being provided on the platform structure for guidable connection with the said guide members to interconnect the platform structure and side frames whilst permitting upwards and downwards movement of the platform structure relative to the side frames, the frames being adapted for movement at least forwards and backwards along a supporting floor surface, and power means for powering said movement of the platform structure in at least said upwards direction, said power means being mounted relative to the frames so as to be movable forwards and backwards therewith.
2. A lifting mechanism according to claim 1 wherein each frame has two upright guide members and the platform structure has two guide elements for each frame.
3. A lifting mechanism according to claim 2 wherein the guide members of each frame are of common height and are linked by top and bottom cross members.
4. A lifting mechanism according to claim 3 wherein the cross members are parallel to each other.
5. A lifting mechanism according to any one of claims 2 to 4 wherein

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the guide members of each frame are parallel to each other.
6. A lifting mechanism according to any one of claims 2 to 5 wherein the guide elements are of common length.
7. A lifting mechanism according to any one of claims 1 to 6 wherein each guide member is a tube and each guide element is a sleeve which fits slidably around the respective tube.
8. A lifting mechanism according to any one of claims 1 to 7 wherein the platform structure comprises a rectangular frame having interconnected elongate peripheral members with an overlying support floor.
9. A lifting mechanism according to any one of claims 1 to 8 wherein the platform structure forms the sole interconnection between the side frames.
10. A lifting mechanism according to any one of claims 1 to 9 wherein the side frames have rollers or wheels for engagement with the floor surface.
11. A lifting mechanism according to any one of claims 1 to 10 wherein locking means is provided for retaining the lifting mechanism in position on the floor surface.
12. A lifting mechanism according to claim 10 and 11 wherein the locking means comprises a brake on the said rollers or wheels.
13. A lifting mechanism according to any one of claims 1 to 12 wherein the power means is arranged for powering movement both

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upwards and downwards.
14. A lifting mechanism according to any one of claims 1 to 13 wherein the power means comprises a motor which is mounted on the platform structure and is connected via one or more shafts to one or more toothed sprockets drivably engageable with at least one chain extending upwardly and fixed at its ends respectively to top and bottom positions on a respective said frame.
15. A lifting mechanism according to claim 14 wherein there are two shafts engageable at opposite ends with two chains on each frame.
16. A lifting mechanism according to any one of claims 1 to 15 wherein the power means comprises an electric motor.
17. A lifting mechanism substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.
18. A load-carrying road vehicle incorporating a lifting mechanism according to any one of claims 1 to 17 wherein the frames are arranged at opposite sides of a load supporting floor of the vehicle.